Medical community had realized long ago that near-sighted persons who wear bifocals have the approximately thirty feet of uncorrected space due to a stationary glass frame with respect to a wearer's face. This uncorrected space results in blurry vision for such wearers of bifocals. Responding to this problem, wearers usually attempt to displace bifocals fore and aft in front of their faces. Usually such displacement covers approximately a distance between a quarter inch and a maximum of approximately one inch before wearers feel comfortable. In response to this problem, quite a few attempts dealing with adjustable frames for a pair of eye glasses have been made.
Thus, the U.S. Pat. No. 5,162,824 to Klemka discloses an adjustable lens spectacle including a rigid front frame and mounted parallel thereto a slidable rear frame. The rear frame is provided with a drive motor contained within a respective temple leg, and a drive means coupling the motor with the rear frame for effecting reciprocation of the rear frame relative to front frame. The frame is further provided with a reversing switch mounted outside the frame. A distance at which the rear frame travels is grossly inadequate to compensate for the uncorrected space mentioned above. Further, a cross plate (11) serving as a guide for the rear frame is esthetically unappealing because the displaceable frame cannot fit the front frame, thereby increasing the overall size of the disclosed pair of eyeglasses. Typically, a wearer of the assembled pair of eyeglasses (10) would experience considerable inconvenience because the overall structure is neither compact nor light.
U.S. Pat. to Kaye sets forth a device for aiding vision of images primarily for magnifying a television picture. The device includes a pair of spectacles, comprising eye-piece lenses mounted in a frame, and binocular objective lenses disposed in front if each eye-piece lens and supported by an extension to the frame of spectacles. The device further has a means for displacing objective lenses along the optical axis.
U.S. Pat. No. 3,659,931 discloses an eyeglasses frame having a manually adjustable means for individually moving each lens toward and away from the wearer's eye to vary the lens-eye separation for optimum focus.
Generally, the known prior art does not disclose a light, compact pair of eyeglasses provided with a pair of lenses synchronously displaceable between a normal position in which the lenses are secured within respective eyepieces and an extended position in which the lenses travel at a distance between a quarter inch to a maximum of one inch.
Typically, the known prior art does not teach a compact pair of eyeglasses provided with a single lens frame controllably displaceable by an actuator, which is received in a pair of temple pieces, between normal and extended positions thereof and a programmable means also mounted in the temple pieces for controlling the actuator, thereby bringing the lens frame to automatically selected positions thereof.
Finally, all of the known prior art devices may rather have a complicated mechanical structure prone to frequent malfunctioning because the wearer should adjust optimum focus every time she uses the frame and because the components are exposed to unnecessary and easily avoidable stresses.